1. Field of the Invention
This invention relates to color imaging systems with strong lateral chromatic aberration, for example for wide angle systems and inherently dispersive systems.
2. Description of the Related Art
Lateral color is one type of wavelength-specific or chromatic aberration. Lateral color characterizes the wavelength-dependent focal length of an optical system due to dispersion in the optical system. Dispersion in the optical system causes rays of light to refract at optical surfaces in a wavelength-dependent fashion. This wavelength-dependent variation becomes more severe as the incidence angle on a particular surface increases. Consequently, lateral color is more problematic in wide angle systems where rays strike the first lens surface at extreme angles of incidence. Lateral color can also be problematic in optical systems that include diffractive optical elements (DOE) due to the inherently dispersive nature of DOEs.
Typically, optical systems are designed to minimize lateral chromatic aberration, often at great expense in terms of optical glass costs, lens system size, and number of lens elements. Perhaps the most difficult optical aberration to correct in super-wide angle imaging systems is that of lateral color. One traditional method involves using large curved lens elements at the front of the lens system combined with a negative achromatic later in the optical train. However, this adds to the cost and complexity of the lens system.
Thus, there is a need for color imaging systems where the effects of lateral color can be controlled without requiring expensive, large or complex lens systems.